Wearables vs. Smartphone Apps: Which Are Better to Count Steps?

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If you think your Fitbit is better at counting daily steps than
your smartphone, you may want to think again. A new study
suggests that many smartphone apps are just as good as
specialized wearable devices at tracking physical activity.

In the study, 14 participants donned a number of wearable devices
and also carried several smartphones loaded with activity apps,
while they walked on a treadmill for a set number of steps
(either 500 or 1,500). The researchers then compared
participants' actual step
count with the number recorded by each of the devices or
apps.

The participants wore three devices on their waist
(the Fitbit
One, the Fitbit Zip and the Yamax Digi-Walker SW-200
pedometer) and three devices on their wrist (the Yamax
Digi-Walker SW-200, the Jawbone Up24 and the Nike Fuelband).
Participants also had one smartphone in each of their pants
pockets: An Apple iPhone 5s that was running three physical
activity apps (Fitbit, Health Mate by Withings and Moves by
ProtoGeo Oy), and a Samsung Galaxy S4 that was running one
physical activity app (Moves by ProtoGeo Oy).

Each participant completed the treadmill walk four times, for a
total of 56 walking trials. Overall, both the wearable devices
and smartphone apps were pretty accurate at tracking steps
counts, the researchers said. [ Best
Fitness Apps for 2015 ]

The waist-worn wearable devices came closest to reflecting
participants' actual step counts: These devices reported step
counts that were between 0.3 percent lower and 1 percent higher
than the participants' actual step count.

The smartphone applications used in the study reported step
counts that were between 6.7 percent lower and 6 percent higher
than actual step counts. Although there will be some variability
in such step counts, depending on where on his or her body a
person keeps the smartphone, it's likely that those apps will
still be pretty accurate if the smartphone is carried in other
locations, such as in a purse or on the hip, said study
researcher Dr. Mitesh S. Patel, an assistant professor of
medicine and health care management at the University of
Pennsylvania School of Medicine

Wearable devices worn on the wrist were more variable in their
step counts, reporting counts that were between 22.7 percent
lower to 1.5 percent higher than the participants' actual step
counts.

Gadgets that track people's physical activity have the potential
to help people become more active, but only about 1 to 2 percent
of U.S. adults own a wearable, whereas more than 65 percent carry
a smartphone, the researchers said.

"Our findings suggest that smartphone apps could prove to be a
more widely accessible and affordable way of tracking health
behaviors," Patel said
in a statement.

The findings may also reinforce people's trust in using
smartphones and wearables to accurately track physical activity.
Patel noted that these gadgets often use step counts to calculate
other measures of physical activity, such as distance walked and
calories burned, so "their accuracy is key."

In an interview
with Live Science last year, Dr. Clay Marsh, who at the
time was chief innovation officer at Ohio State University Wexner
Medical Center, said that a device's accuracy at counting steps
is less important than its consistency. As long as a device is
consistent in the way it measures movement, it can be useful
because it will show your progress, Marsh said.

Because the new study was conducted in a controlled lab setting
with a limited number of devices and applications, the results
should be confirmed in different settings with other devices and
apps, the researchers said.

The study is published today (Feb. 10) in the Journal of the
American Medical Association.